OptionMonster's tracking systemsdetected heavy selling of the November 35 puts. The options were priced at $2.50 to $2.65 and volume totaled 5,144 contracts, almost four times open interest. Most of the activity occurred in a single minute, indicating activity by an institutional investor.

Aflac rose 6.66 percent to $37.81 and is up 22 percent in the last month. The supplemental insurance company would have to fall below about $32.50 for the put seller to lose money on the position.

Other investors purchased calls to express a bullish sentiment toward the stock. The August 39 calls changed hands 2,031 times, rallying from $0.45 to a high of $1.20. The August 38 calls traded for $0.55 to $1.73. Volume exceeded open interest in both strikes.

Overall options activity in Aflac was more than three times average on the session.